The invention relates to an electroacoustic transducer unit for a handsfree device in a vehicle, particularly for the connection to a mobile telephone as the transmission device.
Handsfree devices are very widely used for telephoning in a vehicle, because the user then does not have to hold the mobile telephone in the hand. This is of major importance, to enable him to devote his entire attention to the road traffic and to the steering of the vehicle.
Apart from a type of base station, generally comprising a support for the mobile telephone together with the installed handsfree electronics, known handsfree devices in vehicles have a microphone and a loudspeaker, which are to be connected thereto. Microphones of known handsfree devices are normally fixed to the A-support or panel, partly also to or behind the steering wheel. The loudspeakers are generally constituted by smaller modules, which either have to be fixed in a very complicated manner to the panel or even in the foot space of the passenger. This is due to the fact that for avoiding interference, as well as feedback and echo, there must be no direct, linear acoustic connection between the loudspeaker and microphone of the handsfree device. These extremely disturbing effects more particularly occur in full duplex operation. Besides the fitting of the microphone, the installation of the loudspeaker at an inaccessible location, such as the foot space, is considered to be very disadvantage, inter alia because it is exposed there to dirt and a damage risk.
The problem of the invention is to provide an electroacoustic transducer unit for a handsfree device, which can be easily fitted, retrofitted and which is operationally reliable.
According to the invention this problem is solved by claim 1. The transducer unit or transducer can be positioned close to the head, mouth or ear of a person sitting in the seat and can be fitted to the seat or vehicle. As opposed to a head mount, e.g. an earphone, the transducer unit does not impede the user and when fitted behind the head it is scarcely optically noticed. In particular, the electroacoustic transducer unit has at least one loudspeaker. As a result of the very short transmission path to the ear, it is possible to keep the sound volume low and to drown the disturbing noises occurring in a vehicle.
The transducer unit preferably has a holder or support for fixing to the seat or vehicle, preferably in the vicinity of the headrest of the seat and at least partly between the headrest and seatback. Numerous fixing or fastening possibilities are available.
In particularly preferred manner the support is constructed for fixing to at least one headrest carrier of a headrest and the in particular manual fastening can be released. Thus, use is made of the free space present with most vehicle seats between the lateral headrest carriers and the headrest and seatback or one of the indicted components for housing or fixing the transducer unit. The transducer unit for this purpose can be fixed to and in particular at least partly between two headrest carriers. In the case of the normally columnar headrest carriers, they permit a particularly advantageous fixing. It is advantageously possible to fix and/or release without tools the transducer unit with support and with particular preference it is lockable or clampable. A further fitting possibility is to the vehicle roof, e.g. to the sliding roof, or to the B-support.
According to an embodiment of the invention, the electroacoustic transducer unit has a housing or casing for receiving at least one loudspeaker. The latter is preferably shock absorbing to the outside for safety reasons, preferably as a result of a fitted or enveloping cushioning. It is also possible to have a casing made from shock absorbing material, particularly hard or rigid foam materials and the like. Particularly the areas which in the fixed state are directed towards the front and rear in the vehicle longitudinal direction, can be resilient and preferably cushioned for safety reasons.
In a particularly preferred embodiment of the invention, the casing comprises at least one cavity constructed for receiving at least one transducer or loudspeaker and which is preferably in the form of a resonator chamber for sound amplification for a loudspeaker. In order to improve the sound radiation, the casing or cavity can have at least one sound exit opening, which can in particular be oriented in the forwards direction. As a result of the thus obtained sound radiation in a desired direction, particularly in the direction of the ear or forwards, in the case of limited power or volume of the loudspeaker excellent comprehensibility can be obtained for the operator.
The loudspeaker can be a conventional diaphragm loudspeaker, which can be inexpensively mass produced. Alternatively a piezoelectric loudspeaker can be provided, whose advantages include limited size, minimum wear susceptibility, low energy consumption, low susceptibility to electromagnetic fields occurring in a vehicle and a good frequency response corresponding well to the frequency range of human speech.
Preferably the transducer unit can be locked, particularly in self-arresting manner by means of the support between two headrest carriers and it is preferably provided with receptacles or recesses for said headrest carriers. As the spacing of the headrest carriers in the case of a vertical adjustment of the headrest remains the same, fixing advantageously takes place thereto. By means of receptacles or recesses it is possible for the transducer unit or its casing to at least partly embrace the headrest carriers and thus ensure an adequately reliable connection. In particularly preferred manner the transducer unit or its casing is length-variable, particularly in a telescopic manner. Alternatively it can have an elastic length variability of an inner area of the casing, preferably along the longitudinal axis of the casing. This permits an adaptation to different spacings of fixing points, e.g. headrest carriers. It is possible to produce a universal retrofitting set, which is usable for numerous vehicle seat variants. The transducer unit or the support can have a longitudinal spring suspension, preferably for the casing, so that it can be locked with prestress to and in particular between the headrest carriers. It can also be fixed or locked between the seatback and headrest or in a standard cutout in the headrest.
The longitudinal spring suspension assists the arresting or locking action. It is also possible to house it in the headrest.
The casing can have at least two parts, e.g. two shells. One part can be connected in articulated manner to the remaining casing and is in particular slidable or pivotable with respect thereto. One part preferably contains at least one loudspeaker, which permits an advantageous directing of the sound waves towards the ear or head. At least one sound passage opening and/or at least one loudspeaker can be orientable, e.g. in such a way that sound is emitted towards the front of the vehicle, preferably roughly in the direction of an ear of a person sitting in the seat.
Alternatively to a microphone as the sole electroacoustic transducer unit, according to a variant of the invention with a loudspeaker as the transducer can additionally be associated a microphone means. At least one microphone can be fixed to the support or casing, preferably by means of a microphone holder constructed for this purpose. Thus, in much the same way as for the loudspeaker, the microphone is advantageously located in the vicinity of the head, without it having to be held or carried by the operator.
The microphone means or holder are preferably constructed in such a way that the position and/or orientation of a microphone can be randomly fixed. This is possible by a bracket in the manner of a swanneck or in particular in the form of a flexurally non-rigid, dimensionally stable cable.
For the construction of a complete handsfree device directly connected to the electroacoustic transducer, with the latter can be associated handsfree electronics, which can in particular be placed in the casing or on the support. In conjunction with a directly associated microphone, this leads to a compact, but still easily fittable and advantageously usable handsfree device. There is no need for complicated connections to an external handsfree device. In one variant of the invention the transducer unit is connectable in signal-transmitting manner, preferably by means of a connecting cable, to a mobile telephone, car telephone or some other wireless transmission device. It is also possible to have a wireless signal transmission, e.g. through an infrared transmission path between the transducer unit and the telephone or its base or reception station.
According to a preferred development of the invention at least one loudspeaker can be fixed behind and one microphone in front of the head or mouth of a person sitting in the seat. Thus, not only are they spatially positioned close to the ear or mouth, but additionally through an interruption of a direct transmission line between loudspeaker and microphone through the head, undesired interference effects of a handsfree device such as feedback or echo are avoided.
In order to create a universal transducer unit, with it can be associated its own electric power supply and it or a support or casing can in particular have a receptacle for an insertable battery. Alternatively or additionally a power supply from the mobile telephone is possible.
A preferred construction of the invention can have an elongated, at least partly resiliently compressible casing with a loudspeaker at one end, which has two recesses at both ends, a longitudinal spring suspension being positioned in one long recess. When the longitudinal spring suspension is compressed, the transducer unit can be inserted by means of the lateral recesses between two headrest carriers of a vehicle seat and can be automatically arrested there in positively engaging manner in the vehicle longitudinal direction. Such a transducer unit is manually fixable and releasable again in simple manner. To facilitate getting into the vehicle, the part with the loudspeaker is preferably directed towards the centre of the vehicle and advantageously have a microphone means with holder. The casing can be longer than the spacing of the headrest carriers and is inserted in inclined manner.
For fitting to vehicle seats, e.g. to headrests without carriers, e.g. integral seats, it is possible to bring about fixing with a textile adhesive connection. It would be possible to loop the upper seatback area or headrest area with such an adhesive tape and the transducer unit can be fixed thereto. Another possibility is the arrangement in or on an envelope, which at least partly engages round the upper seat or headrest area and which is e.g. constructed in the manner of a textile covering or the like, together with the receptacle for the transducer unit. A permanent fixing of an electroacoustic transducer on or in a vehicle seat by screwing or the like is possible. It is possible to invisibly wire a connecting cable to a transmission device, preferably a mobile telephone, or a handsfree device within the vehicle seat or on its back.
These and other features can be gathered from the claims, description and drawings and the individual features, either singly or in the form of sub-combinations, can be implemented in an embodiment of the invention and in other fields and can represent advantageous, independently protectable constructions for which protection is claimed here. The subdivision of the application into individual sections and the subtitles in no way restrict the general validity of the statements made thereunder.